Selective Zeolite Catalyst for Alkylation of Benzene with Ethylene to Produce Ethylbenzene

Appl Petrochem Res (2012) 2:73–83 DOI 10.1007/s13203-012-0022-6

KACST FORUM

Selective zeolite catalyst for alkylation of benzene with ethylene to produce ethylbenzene

Mohammed C. Al-Kinany • Hamid A. Al-Megren • Eyad A. Al-Ghilan • Peter P. Edwards • Tiancun Xiao • Ahmad. S. Al-Shammari • Saud A. Al-Drees

Received: 4 July 2012 / Accepted: 27 October 2012 Ó The Author(s) 2012. This article is published with open access at Springerlink.com

Abstract In this work, a selective catalyst of BXE conversion of BZ appeared to be depending strongly on ALKCAT zeolite has been developed with about 30 % of mole ratio of BZ to E at a given temperature. The study has ZSM-5 balanced with kaolinite, and applied for gas-phase shown that the BXE ALKCAT zeolite is active as a catalyst alkylation of benzene (BZ) with ethylene (E). The catalyst for the alkylation reaction and selective to EB compared has been tested in a fixed-bed down-pass flow reactor under with other zeolite catalysts. different conditions of temperatures ranging between 300 and 450 °C with BZ to E mole ratios ranging between 1:1, Keywords Alkylation Á Ethylation Á Ethylbenzene Á 3:1 and 6:1 under atmospheric pressure and space velocity Zeolite ranges between 0.1 and 150 h-1. The BXE ALKCAT zeolite catalyst has been characterized using: scanning electron microscope, X-ray diffraction, specific surface Introduction area, pore volumes, pore size distributions, X-ray photoelectron spectroscopy, and differential thermal analysis, Ethylbenzene is important in the petrochemical industry as and thermo-gravimetric analyses. Ethylbenzene was the an intermediate in the production of styrene, which in turn main product of alkylation, and diethylbenzene isomers is used for making polystyrene, a common plastic material. (ortho-, meta-, and para-) were the minor products. In the In industry, EB is mainly manufactured by the alkylation of case of 1:1 mol ratio of BZ to E, the selectivity of EB about benzene with ethylene via two methods, i.e., the gas-phase 85.5 % at highest conversion of BZ was obtained after 1 h method [1–5] and the liquid-phase method. The gas-phase of reaction on stream at 450 °C. A decrease in the tem- method is the Mobil–Badger technology, which used perature to 300 °C (with 1:1 mol ratio) caused the selec- mostly molecular sieve catalyst, e.g. ZSM families like tivity of EB to decrease to 73.0 %. EB and DEBs yields ZSM-5 and ZSM-22, because of their unique advantages of were found to increase with increasing the reaction tem- highly selective, less toxic, environmentally friendly and perature and decreasing the mole ratio of BZ to E. The readily reproducible in catalytic reactions [6, 7]. Another reason for ZSM-5 zeolite catalyst being used in alkylation of benzene with ethylene is that its proper pore size can M. C. Al-Kinany Á H. A. Al-Megren (&) Á increase the EB diffusion, while it prevents the polyeth- E. A. Al-Ghilan Á S. A. Al-Drees ylbenzene (PEB) to diffuse through the catalyst [3, 4, 8, 9]. Petrochemicals Research Institute, King Abdulaziz City However, ZSM-5 zeolite has high acid strength and acid for Science and Technology, P.O.Box 6086, Riyadh 11442, amount, which easily catalyses the carbon formation from Saudi Arabia e-mail: [email protected] ethylene [10, 11]. Therefore, in this process, the benzene to ethylene molar ratio is about 8–16 which increases the P. P. Edwards Á T. Xiao Á Ahmad. S. Al-Shammari Á needed energy in the fraction unit for the separation of EB S. A. Al-Drees from benzene and transethylbenzene. Inorganic Chemistry Laboratory, Wolfson Catalysis Centre, KACST-Oxford Petrochemicals Research Centre (KOPRC), In addition, the gas-phase method normally is carried University of Oxford, South Parks Road, Oxford OX1 3QR, UK out under moderate pressure (1.0–20.8 MPa) and high 123 74 Appl Petrochem Res (2012) 2:73–83 temperature (573–773 K), which leads to higher energy Catalyst characterization consumption, more cooling systems and strict requirements for the apparatus. Many years’ industrial operation results X-ray diffraction (XRD) showed that the pure ZSM-5 based catalyst suffers from several disadvantages. For example, more byproducts are Measurements were conducted using Brucker diffracto- produced, especially toluene at about 1,000–2,000 ppm, meter D8 which utilizes Ni-filtered CuKa radiation which is much higher than the levels required by the (k = 1.54 A˚ ). Diffraction patterns were obtained with downstream processes; the selectivity toward ethyl ben- X-Ray gun operated at 40 kV and 30 mA with a scan rate zene is low, and the deactivation of the catalyst is so of 4°/min (2h). serious that it requires periodic regeneration. The byproducts and the rapid deactivation of the ZSM-5 catalyst Scanning electron microscope (SEM) for the alkylation are believed to be due to its strong acidity. The crystal size and morphology of BXE ALKCAT cata- Kaolinite has been widely used as binder and balanced lyst were determined with a FEI–NNL200, 5 kV and work material for zeolite catalyst, because it has global pore with distance 5.0 mm. The silicon and aluminum contents of the 105 A mean pore size, which has little effect on the dif- BXE ALKCAT zeolites were obtained using EDAX fusion of the reactants products [12–14]. It also allows the Ametek-Model 60040, 10 kV. easy process and extrudation of the acid catalyst. In this work, 30 wt% of ZSM-5 catalyst has been mixed with X-ray photoelectron spectroscopy (XPS) kaolinite and tested for benzene alkylation with ethylene at low benzene to ethylene ratio; the results show that the low XPS studies were recorded using JEOL JPS 9010MC content of ZSM-5 zeolite catalyst is suitable for low ben- photoelectron spectrometer, using MgKa (1,253.6 eV) zene to ethylene ratio and high stability. This may be radiation from an X-ray source operating at 10 kV and promising to reduce the cycle and save energy. 20 mA, and the base pressure in the analysis was kept in the range from 5 9 10-10 to 1 9 10-9 mbar. The binding energies (BE) were referenced to the C1s level at 284.9 eV. Experimental A estimated error of ±0.1 eV can be assumed for all measurements. Catalyst preparation

The catalyst, BOX ALKCAT has been prepared using Physisorption analysis prilling process The main active component, e.g., ZSM-5 (Si/Al = 25) is mixed with kaolinite at 30:60 and 10 % of Textural properties were determined by nitrogen adsorp- alumina as the binder. These are mixed with a small tion–desorption experiments. The isotherm was measured amount of water to form a slurry. The slurry is shaped into using a Micrometrics ASAP 2010 system. BET surface particles using a prilling machine (36MM, SZCX 160/45, area, pore volume and pore size measurements studies were made in China). The resultant catalyst particles contain carried out using physisorption technique. The adsorption 30 wt% of ZSM-5, which is then dried in static air at for nitrogen was measured at 77 K. Prior to the experi- 450 °C for 5 h to remove the moisture and volatile ments, the samples were degassed under vacuum at 250 °C impurities. for 6 h. The surface area was calculated using the BET method based on adsorption data. The pore size distribution Chemicals and catalysts for mesopore was analyzed from desorption branch of the isotherm by the Parrett–Joyner–Halenda method and the All chemicals were analytical grade; benzene, ethylben- pore size distribution for micropore was analyzed by HK zene (Fluka Chemie 99.5 %), o-diethylbenzenes (Fluka method. Chemie 98.9 %), m-diethylbenzenes (Fluka Chemie 98.9 %), p-diethylbenzenes (Fluka Chemie 98.9 %), 1,3,5- Differential thermal analysis (DTA) and triethylbenzene (Fluka Chemie 98 %) and 1,2,4,5-tetra- thermo-gravimetric analyses (TGA) ethylbenzene (Fluka Chemie 98 %) were used directly without further puriﬁcation. Ethylene gas (purity DTA and TGA were recorded on Perkin Elmer (DTA-7) [99.95 %) was obtained from M/s. Abdullah Hashim for with thermal analysis controller TAC-7/DX. The catalyst industrial gases. Hexane (Fluka Chemie) was of high grade samples were recovered after reaction and dried under and spectroscopically highly pure (purity [99.98 %). vacuum before being analyzed by TGA. 123 Appl Petrochem Res (2012) 2:73–83 75

Catalyst evaluation mole ratios from 1:1 to 6:1 at each temperature. Blank reactor runs were conducted and no significant conver- The catalytic behavior of BXE ALKCAT zeolite catalyst sions were observed under the conditions of alkylation for the alkylation of benzene with ethylene was studied in a reaction. conventional bench-top pilot plant, as shown in Fig. 1, fitted with a fixed-bed down-flow stainless steel reactor Gas chromatographic analysis with an internal diameter of 5 mm and 35 cm long at atmospheric pressure and temperature ranging between 300 Gas chromatographic analysis of the alkylation products and 450 °C. The reactor was coupled to a mass flow meter was performed on Varian 3800 series instrument fitted with to measure un-reacted ethylene. The reactor was heated in a flame ionization detector and a 50 m 9 0.25 mm glass an electrical furnace, and the reactor’s temperature was open tubular capillary PONA column. The column tem- measured by a thermocouple located inside the furnace and perature was programmed as an initial temperature of was controlled by a temperature controller (Cole-Parmer 30 °C for 15 min, then 60 °C for 20 min (heating rate Digi-sense). 1 °C/min) and finally 200 °C for 20 min (heating rate Each time, 1.0 g of catalyst was loaded in the middle of 2 °C/min). the reactor. The feed stock of the alkylation reaction con- The FID detector temperature was 250 °C and that of sisting of benzene and ethylene was introduced at the top of injector 250 °C (for manual injection). The maximum the reactor. Normally, the flow rate of ethylene was column temperature at which the stationary phase is stable 2–22 ml/min with benzene to ethylene mole ratios ranging is 200 °C. Flow rates of zero air (80 lb/in2, 300 cm3/min), from 1:1 to 6:1, respectively, under atmospheric pressure. hydrogen (40 lb/in2,30cm3/min) and He carrier gas The flow rate of ethylene was adjusted through a separate (80 lb/in2,25cm3/min) were applied. Occasional checking thermal mass flow controller (Bronkhorst). The flow rate of showed that the flow rate was almost constant. benzene was controlled through a one channel syringe External standardization method is the analytical pump (Cole-Parmer). The alkylation reaction products method which has been employed for the quantitative were collected in a cooled condenser attached to the end of analysis of the alkylation products. The GC instrument was the reactor and was analyzed using a gas chromatograph. calibrated by analyzing the known composition of a pre- The activity of the catalysts, yield and selectivity of pared calibration mixture (standard mixture) of pure com- alkylbenzenes (ethylbenzene, and o-, p- and m-diethyl- ponents of benzene, ethylbenzene, diethylbenzenes (o-, p-, benzene) and benzene conversion were studied at 300, and m-), triethylbenzene and tetraethylbenzene. GC chro- 350, 400 and 450 °C by changing the benzene to ethylene matogram of standard mixture is shown in Fig. 2.

Fig. 1 Bench-top pilot plant fitted with fixed bed reactor. 1 two-way valve, 2 flow meter, 3 check valve, 4 pump, 5 three- way valve, 6 reactor 7 gas chromatography, 8 recorder

123 76 Appl Petrochem Res (2012) 2:73–83

Fig. 2 Typical separation of the standard mixture of: solvent, benzene, ethylbenzene, diethylbenzenes (o-, m-, and p-), and triethylbenzene

Gas chromatography/mass spectroscopy analysis are small and present a relatively high external surface area with little mesoporosity. The textural parameters of the Identification of the alkylation products was performed on corresponding sample have high BET surface area Shimadzu GC/MS—QP2010. The GC fitted with PONA (228.5 m2/g), pore volume (0.174 cm3/g) and pore size 50 m glass open tabular capillary column. The column (30.4 A˚ ) which is attributed to porous kaolinite, where the temperature was programmed as an initial temperature of pore of kaolinite can range very wide. The use of large pore 30 °C for 15 min, then 60 °C for 20 min (heating rate kaolinite also helps the diffusion of the reactants, and dilutes 1 °C/min) and finally 200 °C for 20 min (heating rate the acidic sites, which is the goal to design the catalysts. 2 °C/min). The injector temperature was 250 °C. Flow rate of He (13 kPa, 155 ml/min) was applied: Ion source tem- X-ray diffraction analysis perature 200 °C, interface temperature 250 °C and detector voltage 0.7 kV. Figure 5 shows XRD pattern(s) of BXE ALKCAT zeolite. The high intensity of peaks in the XRD patterns indicated that the BXE ALKCAT zeolite samples are highly crys- Results and discussion talline materials, in which the main phase is kaolinite and whose main diffraction peaks are seen at 2h of 11° and 25o, Catalyst characterization which is in agreement with the catalyst composition. The rest main diffraction peaks all come from the calcined Physicochemical properties of BXE ALKCAT zeolite ZSM-5 sample. As the ZSM-5 only accounts for 30 wt% of the catalyst, its diffraction peaks are relatively weak. Figure 3 shows SEM images of BXE ALKCAT zeolite. It can be seen from the figure that aggregates of spherical X-ray photoelectron spectroscopy data of BXE ALKCAT beads with irregular shape are prominent. The spherical do zeolite not have well-defined morphologies and most of the deformed spherical beads appear to be more than 1 lmin The XPS technique was applied to investigate the binding size. energies of the states of element between Si and O. The XPS data of curve fitting for the zeolite sample were BET surface area, pore volume and size of zeolite recorded as shown in Figs. 6 and 7. All binding energy referred to C1s = 285.0 eV. Data for the elements detected

N2 adsorption/desorption analysis is a useful tool for were Si 2P1/2, and O 1s at binding energies of 102.1 and examining textural characteristics of porous materials. The 532.1 eV. isotherms for BXE ALKCAT zeolite are displayed in It is shown that the surface compositions of the catalyst Fig. 4. are mainly O, Si and Al, with Si as the dominant element,

The isotherm of the sample is a hysteresis loop at rela- whose state is SiO2. Aluminum existed as Al2O3 form. tively high pressure (p/p0), indicating that the crystal sizes These results are in agreement with the composition of the

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Fig. 3 SEM of BXE ALKCAT zeolites

Fig. 4 BET surface area of zeolite

zeolite and kaolinite, and it is shown that the surface has catalyst. Overall, it was found that the catalyst is thermally less –OH groups, which is the main component of Bronsted stable over a wide range of temperature ranging from 25 to acid site. 1,100 °C as shown in Fig. 8.

Differential thermal analysis of catalyst Catalyst evaluation

In order to investigate the stability of zeolite catalyst at Effect of reaction temperature on benzene conversion various temperatures, DTA was performed on zeolite by heating the sample up to 1,100 °C with a rate of heating The alkylation of benzene with ethylene was carried out at 40 °C/min. The ﬁrst sharp peak at 80 °C might result from 300, 350, 400 and 450 °C over BXE ALKCAT zeolite the water or vapor desorption. The continuous endothermic catalyst. The conversion of benzene and the product curve is due to the loss of the hydroxyl group over the selectivity are presented in Figs. 9, 10, 11 and 12.

123 78 Appl Petrochem Res (2012) 2:73–83

5 2-Theta -Scale

Fig. 5 XRD analysis of the ZSM-5/kaolinite catalyst for the alkylation reaction

Conversion of benzene increases from 300 to 400 °C, and a slight decrease in the conversion of benzene was observed as the temperature was increased further up to 450 °C. Benzene conversions of approximately 6.5, 13, and 63 % were achieved at 300, 350 and 400 °C, respectively, while slightly decrease from 63 to 57 % as the temperature was increased from 400 to 450 °C, respectively, for a reaction time of 0.5 h, and mole ratio of BZ to E 1:1. This can be explained by the endothermicity of the alkylation reaction. High reaction temperature favors the conversion, and also the high temperature can increase the activity of the acidic site; thus, the reaction should be carried out at a relatively high temperature.

Fig. 6 Curve ﬁtting XPS spectrum of O 1s of zeolite The effect of time-on-stream

The effect of time-on-stream on benzene conversion and EB selectivity was studied over BXE ALKCAT zeolite catalyst using a feed stock mole ratio ranging from 1:1 to 6:1 under variable temperatures. Reaction conditions and results are presented in Figs. 9, 10 and 11. It is shown that the BZ:E = 1:1, the BZ conversion drops more quickly than over the other catalysts, while practically no changes are observed in selectivity for EB and DEB isomers after about 2 h on stream. Increase of BZ:E decreases the benzene conversion, which is in fact due to the excessive feeding of benzene, to depress the carbon formation; but, the catalyst has a much stable conversion, which is due the depression of carbon formation by the

Fig. 7 Curve ﬁtting XPS spectrum of Si 2P1/2 of zeolite benzene.

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Fig. 8 Differential thermal analysis (DTA) thermogram of zeolite

7 14

6 12

5 10 1:1 1:1 8 4 3:1 3:1 6:1 6:1 6 3

4 Conversion (mol %)

Conversion (mol %) 2

2 1

0 0 0.5 1.5 2.5 3.5 4.5 5.5 0.5 1.5 2.5 3.5 4.5 5.5 Time on stream (hours) Time on stream (hours) Fig. 10 Conversion of benzene with time for zeolite catalyst at Fig. 9 Conversion of benzene with time for zeolite catalyst at 300 °C 350 °C

Effect of reaction temperature on the yield and selectivity temperature changes from 300 to 400 °C and then of ethylated products decreases as the temperature increased up to 450 °Cas shown in Fig. 14. This is probably due to transalkylation of The major product of the alkylation reaction over BXE DEB isomers with benzene as shown in Scheme 1. ALKCAT zeolite catalyst is EB. The yield of EB increases Based on these results, it is inferred that the increase of as the temperature increases from 300 to 450 °C with the reaction temperature makes more active sites available different mole ratios of BZ to E: the reason has been given for the alkylation reaction, awhile more side reactions before. The maximum yield was obtained about 50 % with also occurs. However, overall, the EB yield increases with 1:1 molar ratio of BZ to E at 450 °C for the reaction time the temperature, due to high increase in the conversion 0.5 h as shown in Fig. 13. rate. The maximum yield 17 % of DEB (o-, m-, and p-) Selectivity for EB was affected by temperature. The isomers was obtained at 400 °C with mole ratio of BZ to E selectivity for EB decreased constantly as the temperature 1:1. There is variable trend of the formation of DEB iso- increased from 300 to 400 °C and then increases as mers under the same mole ratio BZ to E and variable the temperature increases up to 450 °C as shown in temperatures. The yield of DEB isomers increases as the Fig. 15. The increase in selectivity is probably due to 123 80 Appl Petrochem Res (2012) 2:73–83

70 mole ratios of BZ to E from 1:1 to 6:1 over BXE ALK- CAT zeolite catalyst at variable temperatures, and the 60 results are presented in Figs. 16, 17 and 18. The yield of ethylbenzene shows a signiﬁcant decline as mole ratios of benzene to ethylene increased from 1:1 to 6:1 at temper- 50 atures of 300, 350, 400, and 450 °C. This is because of the increased dilution of ethylene by benzene. With lower 40 1:1 ethylene content in the feed, the probability of ethylene 3:1 interaction with benzene is reduced and a lower ethyl- 30 6:1 benzene yield is obtained. In addition, the excessive feeding of benzene would give a overall low conversion, even all the ethylene is consumed. The maximum of about Conversion (mol %) 20 50 % yield was obtained with 1:1 molar ratio of BZ to E at 450 °C. 10 However, yield for the other alkylated products such as diethylbenzene (o-, m-, and p-) isomers decreased as the 0 mole ratio of BZ to E increased. The increase in the yield 0.5 1.5 2.5 3.5 4.5 5.5 of EB and diethylbenzene isomers results from a high Time on stream (hours) conversion of BZ as the mole ratio of BZ to E decreases. At higher mole ratios of BZ to E, the accessibility of ethyl Fig. 11 Conversion of benzene with time for zeolite catalyst at cations to yield diethylbenzene isomers by further alkyl- 400 °C ation of EB was reduced. Selectivity for EB increased as the ratio of benzene to 70 ethylene increased with lower conversion of benzene. The same trends were observed at temperatures of 300, 350, 60 400, and 450 °C. The maximum selectivity to EB (85 %) with higher conversion of benzene was obtained with a 50 mole ratio of 1:1 at 450 °C, while 73 % with 1:1 at 300 °C.

40 1:1 Coke formation 3:1 30 6:1 In the alkylation of BZ with E, the deactivation of catalysts usually occurs as active sites are blocked by coke forma-

Conversion (mol %) 20 tion. The coking mostly results from the oligomerization of ethylene, because activated ethylene easily reacts with other ethylene molecules to form higher polymer. This is 10 the reason the industry always use excessive benzene, which is to increase the ethylene benzene selectivity and 0 depress the coke formation. The carbon balance was cal- 0.5 1.5 2.5 3.5 4.5 5.5 culated as the following: (1) number of moles of carbon of Time on stream(hours) benzene and ethylene in the feedstock, (2) number of moles Fig. 12 Conversion of benzene with time for zeolite catalyst at of carbon of the unreacted ethylene, and reaction products 450 °C (unreacted benzene, ethylbenzene, and m-, p-, o-diethylbenzenes), and (3) carbon deposited on the catalyst as transalkylation reactions between benzene and diethyl- obtained from TGA results (Table 1). It was found that the benzene (o-, m-, and p-) isomers as shown in Scheme 1. errors are ranging from 5 to ±10 %.

The effect of feed stock mole ratio the yield and selectivity of ethylated products Conclusion

The effect of feed stock mole ratio on ethylbenzene yield A kaolinite-supported ZSM-5 zeolite catalyst has been and product selectivity was studied by varying the feed prepared using prilling process. The catalyst has stable 123 Appl Petrochem Res (2012) 2:73–83 81

Fig. 13 Yield of EB at variable 60.00 temperatures using different 50.00 mole ratio of BZ:E under 50.00 44.23 atmospheric pressure 38.20 40.00 30.00 30.00 22.22 19.17 EBz Yield 20.00 10.46

Yield (mole %) 8.80 8.58 10.00 4.20 3.85 3.13 0.00 300°C 350°C 400°C 450°C 300°C 350°C 400°C 450°C 300°C 350°C 400°C 450°C

1:1 3:1 6:1

Fig. 14 Yield of EB and DEB 60.00 at variable temperatures using 50.00 50.00 different mole ratio of BZ:E 44.23 under atmospheric pressure 40.00 38.20

30.00 30.00 EBz Yield 22.22 19.17 DEBz Yield 20.00 17.35

Yield (mol %) 10.46 8.84 8.80 8.58 10.00 6.51 4.20 2.13 3.85 2.22 3.13 2.79 0.00 1.56 1.52 0.00 0.91 1.40 0.00 300°C 350°C 400°C 450°C 300°C 350°C 400°C 450°C 300°C 350°C 400°C 450°C 1:1 3:1 6:1

structure, with surface mainly composed of SiO2. The catalyst has been tested in the alkylation of the benzene with ethylene. It is found that the catalyst showed high selectivity to ethylbenzene at low temperature and high benzene to ethylene ratio. The prepared catalyst has high stability at high benzene to ethylene ratio, and high yield of ethylbenzene. The increase of reaction temperature gives higher benzene conversion, but a low with more side products. Higher benzene to ethylene ratio helps to depress the side reaction, but lead to lower conversion of benzene due to the excess Scheme1 Transalkylation reaction of diethylbenzene isomers with benzene feeding.

Fig. 15 Selectivity of EB at 120.00 variable temperatures using 100.00 100.00 100.00 100.00 94.50 90.36 94.08 84.98 85.27 87.28 different mole ratio of BZ:E 83.08 80.50 82.17 under atmospheric pressure 80.00

60.00 Selectivity of EB 40.00

Selectivity % 20.00

0.00 300°C 350°C 400°C 450°C 300°C 350°C 400°C 450°C 300°C 350°C 400°C 450°C

1:1 3:1 6:1

123 82 Appl Petrochem Res (2012) 2:73–83

Fig. 16 Yield of EB using 60.00 different mole ratio of BZ:E at 50.00 variable temperatures and under 50.00 44.23 38.20 atmospheric pressure 40.00 30.00 30.00 22.22 EBz Yield 19.17 20.00 10.46 8.80 8.58 Yield (mole %) 10.00 4.20 3.85 3.13 0.00

1:1 3:1 6:1 1:1 3:1 6:1 1:1 3:1 6:1 1:1 3:1 6:1

300°C 350°C 400°C 450°C

Fig. 17 Yield of EB and DEB 60.00 using different mole ratio of 50.00 BZ:E at variable temperatures 50.00 and under atmospheric pressure 44.23 40.00 38.20 30.00 EBz Yield 30.00 22.22 DEBz Yield 19.17 20.00 17.35 Yield (mol %) 10.46 8.80 8.58 8.84 10.00 6.51 4.20 3.85 3.13 1.56 2.13 2.79 2.22 0.70 0.00 1.52 0.91 1.40 0.00 1:1 3:1 6:1 1:1 3:1 6:1 1:1 3:1 6:1 1:1 3:1 6:1

300°C 350°C 400°C 450°C

Fig. 18 Selectivity of EB using 120.00 different mole ratio of BZ:E at 100.00 100.00 94.50 94.08 variable temperatures and under 90.36 87.28 84.62 83.08 85.27 82.17 84.98 atmospheric pressure 80.00 72.92 71.83

60.00 Selectivity of EB 40.00 Selectivity % 20.00

0.00 1:1 3:1 6:1 1:1 3:1 6:1 1:1 3:1 6:1 1:1 3:1 6:1

300°C 350°C 400°C 450°C

Table 1 Thermal gravimetric Starting weight (g) Un-subtracted weight (%) Final weight (g) Balance (g) analysis (TGA) results for carbon deposition balancing Zeolitea 11.238 85.85130 9.648 1.59 with 6:1 mol ratio at variable b temperature Zeolite 10.282 85.60697 8.802 1.48 300 °C; Zeolitea 6:1 10.658 83.47701 8.907 1.751 300 °C; Zeoliteb 6:1 10.275 82.67406 8.497 1.778 350 °C; Zeolitea 6:1 10.366 84.58893 8.769 1.597 350 °C; Zeoliteb 6:1 9.429 84.25536 7.955 1.474 400 °C; Zeolitea 6:1 11.191 88.01292 9.861 1.33 a Heating rate: 10 ml/min 400 °C; Zeoliteb 6:1 12.830 87.37062 11.217 1.613 b Heating rate: 40 ml/min 123 Appl Petrochem Res (2012) 2:73–83 83

There is carbon deposition occurred over the BXE 3. Hansen N et al (2008) Theoretical investigation of benzene ALKC at catalysts, which accounts for about 10 % of alkylation with ethene over H-ZSM-5. J Phys Chem C 112(39): 15402–15411 carbon, even the catalyst is still active, which suggest that 4. Hansen N et al (2010) Quantum chemical modeling of benzene the carbon may not be the poison for the catalyst active ethylation over H-ZSM-5 approaching chemical accuracy: a site. hybrid MP2:DFT study. J Am Chem Soc 132(33):11525–11538 The optimal operation conditions for the BXE ALKCAT 5. Kartal OE, Onal I (2008) Synthesis of ZSM-5 from modiﬁed clinoptilolite and its catalytic activity in alkylation of benzene to are relatively high temperature 350–400 °C and high ben- ethylbenzene. Chem Eng Commun 195(8):1043–1057 zene to ethylene ratio to give high yield and high selec- 6. Bassler EJ et al (1999) Upgrade by catalytic process technology. tivity of ethylbenzene over the catalyst. Hydrocarbon Eng 4(7):36–40 7. Dwyer FG (1981) Mobil/Badger ethylbenzene process—chem- Acknowledgments We would like to thank Dr. Turki bin Saud bin istry and catalytic implications. Chem Ind (Dekker) 5:39–50 Mohammad Al Saud, the Vice President for Research Institutes for 8. Ebrahimi AN et al (2011) Modiﬁcation and optimization of his valuable support and funding the joint research. Also, I would like benzene alkylation process for production of ethylbenzene. Chem to thank the alkylation research team: Eng. Khalid S. Al-Ghamdi, Eng Process 50(1):31–36 Abdullah J. Al-Ghamdi, Sami D. Al-Dress, Waleed A. Al-Suwaylih 9. Hansen N et al (2009) Analysis of diffusion limitation in the and Sami D. Al-Zahrani. alkylation of Benzene over H-ZSM-5 by combining quantum chemical calculations, molecular simulations, and a continuum Open Access This article is distributed under the terms of the approach. J Phys Chem C 113(1):235–246 Creative Commons Attribution License which permits any use, dis- 10. Liu J et al (1999) The carbon depositing behavior and its kinetic tribution, and reproduction in any medium, provided the original research in benzene alkylation process over high silicate ZSM-5 author(s) and the source are credited. zeolite. J Therm Anal Calorim 58(2):375–381 11. Song Y et al (2006) Coke burning behavior of a catalyst of ZSM- 5/ZSM-11 co-crystallized zeolite in the alkylation of benzene with FCC off-gas to ethylbenzene. Fuel Process Technol 87(4): 297–302 References 12. Hassan M, El-Shall H (2009) Texture and microstructure of thermally treated acid-leached kaolinitic clays. Adsorpt Sci 1. Al-Kinany MC, Al-Khowaiter SH (1998) Ethylation and isopro- Technol 27(7):671–684 pylation of benzene using superacid catalyst. In: Proceedings of 13. Suraj G et al (1997) The effect of micronization on kaolinites and 15th World Petroleum Congress. vol 2, pp 830–834 their sorption behavior. Appl Clay Sci 12(1–2):111–130 2. Cejka J, Wichterlova B, Bednarova S (1991) Alkylation of 14. Westlake DJ, Atkins MP, Gregory R (1985) The use of layered toluene with ethene over H-ZSM-5 zeolites. Appl Catal A 79(2): clays for the production of petrochemicals. Acta Phys Chem 215–226 31(1–2):301–308

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